Since the early 1990s, scientists have warned that the Conowingo Dam loomed as an ominous threat to the Chesapeake. When the reservoir behind the massive 100-foot dam filled, more sediment and nutrients would begin pouring down the Susquehanna River.

For nearly as long, dealing with the issue has been largely put off; the reservoir issue has always been considered a problem for the future.

The plastic bottles and snack bags and mixed woody debris form a small but dense raft of litter that bobs gently at the edge of the Anacostia River in Washington, DC.

It’s an unusually small mass of litter. Dry weather has brought temporary relief from the surge of trash that washes into the river with each rainfall.

And this particular jumble of litter is about to exit the ecosystem. It lies between the big tubular arms of a “trash trap” that catches litter in a grimy hug as it emerges from an outflow pipe at the river’s shore.

River herring and eels, at first glance, don’t seem to have much in common. Eels spawn far out in the ocean but swim to freshwater rivers to live out most of their lives. River herring spawn in freshwater rivers, but spend most of their lives in the ocean.

And river herring — alewife and blueback herring — look like fish, while eels look like snakes, even though they are fish.

Maryland’s Department of Agriculture has proposed new nutrient management regulations to curb the amount of manure entering the Chesapeake Bay.

The state initially introduced its nutrient management regulations last year, but pulled back the document because of farmers’ concerns that it was too stringent and environmentalists’ worries that it didn’t go far enough. The new approach seeks to balance the concerns of both groups as well as those of water-quality scientists, who had advised the state on the best methods of reducing nitrogen.

The original proposal — to be implemented by 2016 — forbade any application of fertilizer between Nov. 15 and Feb. 28. It also said that farmers had to incorporate organic nutrients within 72 hours of application.

Every spring and summer, Marylanders will head to the shoreline restaurants just as their grandparents did and enthusiastically dig into all things crab: crab cakes, crab imperial, crab drip and good old-fashioned steamed crabs.

But unlike in their grandparents’ day, those “Maryland-style” crab dishes they’re enjoying probably didn’t come from the Chesapeake, or anywhere near it. About 98 percent of the crabmeat served in Maryland each year is imported from Venezuela or Indonesia. Even many of the steamed crabs hail from the Gulf of Mexico.

Steve Vilnit, director of fisheries marketing for the Maryland Department of Natural Resources, does not expect that number to change overnight. But he has launched a campaign to at least educate Marylanders about what they’re eating, with the hope that more of them will start asking for Maryland crab.

Captain John Smith may not have made it to New York or the Blue Ridge Mountains, but the trail that bears his name may now take modern adventurers to such far-flung destinations.

U.S. Interior Secretary Ken Salazar on May 16 announced that he was adding four connecting rivers — the Susquehanna, Chester, Upper Nanticoke and upper James — to the Captain John Smith Chesapeake National Historic Trail.

Their designation as “historic components” allows the National Park Service, which administers the trail, to provide technical and financial assistance to state agencies and local organizations to promote and manage the trail.

Brian Rawlings stares down into a hydrilla bed on Mattawoman Creek, mayflies circling his face. Suddenly, a large gray mass begins to move. He pulls back his arm and shoots an arrow into the heart of a snakehead.

After the atta-boys, Rawlings’ friend Austin Murphy measures the fish: 35 inches. Its weight: close to 17 pounds, the size of a small toddler. Murphy whacks the whipsawing fish with a baseball bat to immobilize it. Then, the men cut out the gills to make sure the catch is good and dead.

Pennsylvania Department of Environmental Protection Secretary Michael Krancer has rejected a request from the Pennsylvania Fish and Boat Commission to list the Susquehanna River as impaired after the discovery of a large number of smallmouth bass with black lesions on them.

In an April letter to Fish and Boat Commission Executive Director John Arway, Krancer said he shared the concerns about the Susquehanna. But listing the river wouldn’t solve the problems, he said, because no one had yet identified the pollutant that was causing the lesions.

The lesions have been showing up in smallmouth bass along a 98-mile stretch from the Holtwood Dam to Williamsport for three decades, but anglers report that they are seeing it more in recent years. While the fish, called “blotchy bass” or “black spot bass,” are safe to eat and handle, the number of infected fish was alarming enough for Arway to make his request.

Earlier this spring, it looked like Virginia had the wind at its back in the state’s quest to become a leader in alternative energy. But that smooth sailing has hit rough waters.

Gamesa Energy and Huntington Ingalls Industries, which had jointly announced plans to build the state’s first offshore wind turbine, pulled the plug on the project. Gamesa will instead focus on building the turbine off the coast of the Spanish Canary Islands, where there are fewer regulatory hurdles.

Gamesa spokeswoman Susana Sanjuan said the company has been committed to Virginia, but switched gears because of uncertainty on federal energy policy, possible tax breaks, a committed market for wind power, and an offshore grid to carry the electricity.

The Atlantic States Marine Fisheries Commission is preparing to implement a commercial tagging program for all states with commercial striped bass fisheries and to increase penalties for poaching.

The commission approved for public comment Draft Addendum II to Amendment Six to the Interstate Fishery Management Plan for striped bass. The draft amendment, which is going out for public comment shortly and will likely not be implemented until 2014, follows the recommendations of the Interstate Watershed Task Force. The task force was seeking ways to curb commercial striped bass poaching.

April showers never materialized in the Bay watershed, as monitoring by the U.S. Geological Survey showed river flows into the Chesapeake were the lowest on record for the month.

USGS monitoring showed that freshwater flows from the Chesapeake Bay’s major tributaries averaged 56,100 cubic feet per second in April. That’s only about 40 percent of the 144,000 cfs average for the month during 76 years of USGS monitoring. The previous low was 59,000 cfs in 1995.

For 35 of the 38 years that Don Webster has worked as a University of Maryland extension agent, he's been trying to move the state into oyster aquaculture.

He came close when William Donald Schaefer was governor in the 1990s, when the public fishery nearly collapsed under the weight of two parasitic diseases. But ultimately, the state's watermen resisted it. He thought the state might get there in 2004, under Robert Ehrlich Jr., the state's first Republican governor in nearly 40 years. But while the Ehrlich administration made some progress, the few aquaculture businesses that developed during his tenure could hardly be called an industry.

A new study is in full swing to examine whether the Conowingo Dam is choking off a vital supply of natural materials needed to sustain wildlife habitat located in the lower 10 miles of the Susquehanna River and the Upper Chesapeake Bay.

Most of the concern about the dam has focused on the deluge of sediments that will head downstream when it fills. But some biologists say that not enough of certain types of sediment is getting past the dam, which hurts downstream habitats.

“A certain amount of alluvial material — whether sand, gravel, boulders or leaf litter — is a natural component of river waters and its movement downstream is a normal function,” said Larry Miller, who served as Susquehanna River coordinator for the U.S. Fish & Wildlife Service before becoming project leader at its Allegheny National Fish Hatchery.